Recent content by Kawrae

The problem is to find the area of r = 4cos3θ. I know the formula for finding the area in polar coordinates is ∫ (from α to β) ½r²dθ. I substituted into this formula the given equation and got: A = ½ ∫ (from 0 to 2π) (4cos3θ)²dθ = ½ ∫ (from 0 to 2π) (16cos²9θ)dθ = 8 [(9/2)θ +...

Find the vector that satisfies the stated conditions: Length (17^1/2) and same direction as v = <7,0,-6>. The book gives the answer as being u = (1/5)<7,0,-6>. Having some trouble getting this answer... here is how I went about attempting to solve it: 1. Finding the vector length of the...

Here is the question: A closed rectangular box with a volume of 16ft^3 is made from two kinds of materials. The top and bottom are made of material costing 10 cents per square foot and the sides from material costing 5 cents per square foot. Find the dimensions of the box so that the cost...

>> Calculate approximately how many molecules of ATP are required for a standard muscle like the biceps during the contraction phase of a single twitch. I honestly do not even know where to begin here... I don't think he wants us to go through and just outline Glycolysis/Kreb's Cycle/ETC...

A capacitor in an RC circuit is charged to 68.0% of its maximum value in 0.980 s. What is the time constant of the circuit? >> I know the time constant is equal to Q/(Q/t) and that t = 0.980 s. I also know that Q = CE and E is a constant. But they don't tell me the capacitance to use... Bah...

? I'm confused on what I'm supposed to integrate -> the original I(t) that they gave me? Won't that just give me the current when they want the charge?

An electric current is given by the expression I ( t ) = 115 sin(120t), where I is in amperes and t is in seconds. What is the total charge carried by the current from t = 0 to t = 1/120 s? >> Since I = deltaQ/deltaT I rearranged and solved for Q = I(deltaT). Then I took T=0 and...

I know this isn't a physics problem, but it's due tomorrow and I'm really stuck :( Calculate the mass, in grams, of calcium ion dissolved in the water of a 40.0 gallon hot-water tank saturated with calcium phosphate. (Ksp calcium phosphate = 2.0e-29, 1.00gal=3.80L). >> I'm really lost...

Okay, I know what Eo is but how do I find the other variable in that equation?

When a potential difference of 162 V is applied to the plates of a parallel-plate capacitor, the plates carry a surface charge density of 33.0 nC/cm^2. What is the spacing between the plates? >> I'm rather confused with this question. I know that deltaV = Ed and I tried solving for d, but I...

1. Through what potential difference would an electron need to be accelerated for it to achieve a speed of 50.0% of the speed of light, starting from rest? The speed of light is c = 3.00 108 m/s. >> I'm really not too sure what to do with this problem. I took .50*3.00e8 and got 1.50e8...

Oh yes you're right, I must have copied it wrong. Okay, one more question: does anyone know the chemical formula for potassium formate?? I can't seem to find it anywhere in my book or online...

Please any help would be greatly appreciated :(

1.00 g of formic acid and 1.00 g of potassium formate acid are dissolved in enough water to give 100.0 ml of solution. Calculate the pH of the solution. >> I'm not really sure how to start this. These are two acids being mixed together... Would there be a reaction? I'm very confused on how...

Um okay, the distance from the bottom left corner to the top left corner is 20.0 cm, the distance from the bottom left corner to the top right corner is 72.8cm and the distance from the bottom left corner to the bottom right corner is 70.0cm. I'll try and post my work here, but I don't know...